The present invention relates to the preparation of one or more metal and/or metal compounds containing catalysts or catalyst precursors starting from complex cyanides. The present invention also relates to the use of catalysts obtained from cyanide complexes in the production of hydrocarbons from carbon monoxide and hydrogen as well as in the hydrodesulphurisation of hydrocarbonaceous materials.
One of the problems often encountered in the manufacture of metal-containing heterogeneous catalysts is the phenomenon of reaction of the metal ion(s) to be incorporated on the carrier with the carrier. This can already happen during the initial contact of the metal ion(s) to be incorporated on the carrier and is many times observed when subjecting the appropriate metal ion(s) containing carrier to a customary thermal treatment which is normally used to transfer the system into the catalytically desired species or to stabilise the system obtained or both. In particular, it is a well-known problem for iron and/or manganese containing catalyst, but also nickel and cobalt containing catalysts are difficult to manufacture because of this unwanted tendency of metal ion/support interaction.
It should be noted that complex cyanides can be used as starting materials in the preparation of supported catalysts by firstly introducing an appropriate cyanide to a support, or alternatively precipitating a complex cyanide on a support iron a metal salt and an appropriate cyanide followed by activating the cyanide thus introduced. For instance, in U.S. Pat. specification 4,186,112 a process is described for reducing carbon monoxide by means of hydrogen using supported catalysts prepared by precipitating a polymetal salt of a hydrocyanic acid which is subjected to a so-called forming step, after separating and drying the precipitated salt. It is reported that forming takes place when thermally decomposing the salt in contact with hydrogen or a mixture of hydrogen and carbon monoxide. It is also possible to carry out the thermal decomposition under vacuum.
It is further known (J. of Cat. 71], 111-118 1981]) to produce finely dispersed metals in zeolites by reacting a metal-exchanged zeolite and an anionic, metal-containing coordination compound, specifically a water-soluble, metal cyanide complex followed by subsequent reduction with hydrogen at a temperature of 400.degree. C.
It has now surprisingly been found that very interesting catalysts or catalyst precursors can be obtained which do not suffer (or only to a marginal extent) from unwanted metal ion/support interaction when complex cyanide containing carriers are subjected to a decomposition treatment under oxidative conditions. In general, it has been found that, especially after an activation step, more active and more stable catalysts will be obtained.